For such bearing devices, ball bearings or roll bearings are used to a great extent, and these should be well embedded in oil or grease for lubrication. In bearings of this type it is desired to avoid leakage of the grease or the oil to the space outside of the bearing, but it is also important to avoid the entry of rigid foreign particles into the ball bearing or roll bearing. Therefore, it has already been proposed for this purpose to provide two sealing rings or surfaces acting after each other, in the form of an elastomeric body usually of rubber, in contact against smooth surfaces, whereby the ring positioned adjacent to the bearing has been intended primarily to prevent leakage of grease and oil to the outside, whereas the ring positioned more remote from the bearing was intended primarily to prevent the entry of rigid foreign particles into the bearing. Of course, the two sealing rings will also each function as a security or back-up for the specific purpose for which the other sealing ring is primarily intended. The sealing rings, usually made from rubber, are shaped with a sealing lip, contacting a smooth cylindrical metallic surface.
Sealing devices of this type necessarily involve a lot of different structural details, such as the two elastomeric rings and the two metallic surface parts against which the elastomeric rings are in contact, and often some additional protection parts. Both the elastomeric rings and the metallic surfaces contacted by the elastomeric rings are subject to wear, and therefore it has earlier been regarded desirable that each of these parts should be replaceable. Accordingly, all of the components of the sealing device were usually mounted at the place of manufacture of the machine.
Applicants have found that the wear of the elastomeric ring as well as of the metallic surfaces is promoted to a substantial extent if these parts are not mounted in the exactly correct position relative to each other when mounting together with the bearing, especially as to their position in axial direction. Applicants have also found that if the sealing device is mounted or assembled together at the machinery workshop when building it into the machine concerned, the mounting is often done incorrectly. This may stem from lack of skill of the worker, but perhaps to a greater degree stems from the fact that he usually or frequently does not have at his disposal such alignment devices, jigs or the like, which are available to the manufacturer of the sealing device. Accordingly, applicants are of the opinion that it is advantageous if the entire sealing device is arranged in such a way that it can be delivered to the manufacturer of the machine without the component being assembled together and mounted in the machine manufacturer's workshop, even if such a mounting in the form of a unitary aggregate would mean that when some singular component becomes worn, this can no longer be replaced individually, but the entire sealing aggregate will have to be replaced. By making the sealing device in the form of a closed aggregate, other advantages are also gained, such that the useful life of the device will be longer so that it becomes economically defensible to make the sealing device in a way which precludes the easy replacement of some separate part thereof. Thus, it is advantageous that by building the sealing devide into a closed or unitary aggregate, it is possible more easily to assemble the elastomeric rings and the metallic parts contacted by them in such a way that the component parts are well protected against damage during transport, storing or other handling. Also, the dimensions, especially those in the axial direction, of the aggregate device can be less as compared with the corresponding dimensions of a device having releasable and replaceable component parts. By mounting the components as a unitary aggregate, the possibility of conducting away heat generated within the aggregate can be improved, and this may be further enhanced by providing protection means for enclosing the parts within the aggregate in a suitable way, whereby the friction-generated heat between the elastomeric ring and the contact surfaces can be removed in an advantageous way.
The invention thus relates to a sealing device for bearings, especially roll bearings, in which two sealing places or areas are provided in series, each of which comprises a sealing lip made from an elastomer, preferably rubber, and arranged on one single ring of the same elastomer, for contacting a surface which is cylindrical at the point of contact, the sealing ring being attached to a metallic liner.
Generally in accordance with the invention, the sealing lips are arranged to extend from one single ring-formed part, but to mutually different radial differences from the axis of the sealing device, the sealing device being enclosed in a casing comprising two parts, one of the parts having a Z-shaped profile and the other one having an L-shaped profile, so that the outermost parts of the two parts, which are at least substantially cylindrical, tightly contact each other, the edge of one part being folded over a cavetto-shaped part of the other one, the inner one of the two cylindrical parts forming a contact surface for one of the sealing lips, whereas the at least substantially cylindrical surface of the part of Z-shaped profile adjacent to the shaft forms a contact surface for the other sealing lip.
The invention will be described hereafter in connection with a preferred form of execution illustrated in the appended drawing, but it is to be understood that the invention is not limited to this specific form, but rather that different modifications may exist within the scope of the invention.